Fig. 1: ESR1 expression decreases in muscle stem/progenitor cells at the concave side of AIS patients.

a Representative immunofluorescent staining of bilateral para-spinal muscle sections from an AIS patient. Cryosections were obtained from the convex and concave sides of AIS patients. The cryosections were stained with anti-Laminin antibody. Red indicated laminin; Blue indicated DAPI staining of nuclei. The merged images were shown. Scale bars: 100 μm. b Statistical analysis of the cross-sectional area (CSA) of myofibers. At least 350 fibers were analyzed for each sample. Error bars indicated standard deviation (n = 6). **P < 0.01. c Muscle tissues harvested from the concave and convex side of AIS patients were subjected for scRNA-seq. Samples from two patients were used. Total 16,930 cells were analyzed. The UMAP plots of main cell types for muscles originated from concave and convex side were shown. FAPs indicated fibro/adipogenic progenitors; ECs indicated epithelia cells; SMCs indicated smooth muscle cells; MuSCs/progenitors indicated muscle stem/progenitor cells. d Dot plot of highly expressed genes in each cell type. The size of dots indicated the percentage of cells expressing the designated genes. The color of dots represented gene expression level. e Violin plot of highly expressed genes in each cell type. f Percentage of each cell type at the concave and convex side. g UMAP plots of genes marked muscle stem/progenitor cells. h Pathway enrichment analysis of differentially expressed genes in muscle stem/progenitor cells located at the concave and convex side of AIS patients. Red bars indicated the enriched terms up-regulated in muscle stem/progenitor cells located at the concave side. Blue bars indicated the enriched terms down-regulated in muscle stem/progenitor cells located at the concave side. The enriched terms related to myogenesis were highlighted by the red solid frames and the terms related to estrogen signaling were highlighted by the red dashed frames. i Dot graph of ESR1 and ESR2 expression in each cell types identified in muscle located at the concave and convex side of AIS patients, respectively. j RT-qPCR analysis of ESR1 and ESR2 gene expression levels in muscle stem/progenitor cells isolated from para-spinal muscles derived from non-scoliosis (NS, n = 5), congenital scoliosis (CS, n = 8) and adolescent idiopathic scoliosis (AIS, n = 25) patients. Error bars indicated standard deviation. **P < 0.01; ns indicated no significant changes. k ELISA analysis of ESR1 level in muscle stem/progenitor cells isolated from para-spinal muscles derived from non-scoliosis (NS, n = 5), congenital scoliosis (CS, n = 8) and adolescent idiopathic scoliosis (AIS, n = 25) patients. Error bars indicated standard deviation. **P < 0.01; ns indicated no significant changes.